using System.Collections;
using System.Collections.Generic;
using Godot;
using System;



namespace Rokojori
{
  [Tool]
  [GlobalClass, Icon("res://Scripts/Rokojori/Rokojori-Action-Library/Icons/Scatterer.svg") ]
  public partial class Scatterer:Node3D
  {
    [Export]
    public bool update = false;
    [Export]
    public bool updateAlways = false;
    [Export]
    public Node3D[] containersToClearNodes;
    [Export]
    public bool clearContainers = false;

    [Export]
    public bool removeDiscarded = false;

    [Export]
    public int READ_ONLY_createdPoints = 0;
    [Export]
    public int READ_ONLY_instantiatedPoints = 0;
    [Export]
    public int READ_ONLY_reusedPoints = 0;
    [Export]
    public int READ_ONLY_remappedPoints = 0;


    public override void _Process( double delta )
    {
      if ( clearContainers )
      {
        clearContainers = false;
        ClearContainers();
      }

      if ( ! ( update || updateAlways ) )
      {
        return;
      }

      update = false;

      ScatterAndInstantiatePoints();
    }

    public void ClearContainers()
    {      
      Arrays.ForEach( containersToClearNodes,
        c => 
        { 
          Nodes.RemoveAndDeleteChildren( c );
        }
      );
    }

    class InstantiatedScatterPoint
    {
      public string hash;
      public ScatterPoint scatterPoint;
      public Node3D output;
    }

    Dictionary<string,InstantiatedScatterPoint> _instantiatedPoints = new Dictionary<string, InstantiatedScatterPoint>();
  
    Dictionary<Scatterer,int> _scattererIDs = new Dictionary<Scatterer, int>();

    int GetScattererID( Scatterer s )
    {
      if ( ! _scattererIDs.ContainsKey( s ) )
      {
        _scattererIDs[ s ] = _scattererIDs.Count;
      }

      return _scattererIDs[ s ]; 
    }

    string GetScatterPointHash( ScatterPoint p )
    {
      var scatterID = GetScattererID( p.creator ) + ":" + p.creatorID;

      return scatterID;
    }

    public void ScatterAndInstantiatePoints()
    {
      if ( _instantiatedPoints.Count == 0 )
      {
        ClearContainers();
      }

      var points = Scatter( new List<ScatterPoint>() );

      READ_ONLY_createdPoints = points.Count;
      READ_ONLY_instantiatedPoints = 0;
      READ_ONLY_reusedPoints = 0;
      READ_ONLY_remappedPoints = 0;

      var usedPoints = new HashSet<string>();

      points.RemoveAll( p => ! p.visible );

      points.ForEach( p =>       
        {
          var hash = GetScatterPointHash( p );

          if ( ! CanReuse( hash, p ) )
          {
            return;
          }

          var existing = _instantiatedPoints[ hash ];           
          existing.scatterPoint = p;
          existing.scatterPoint.UpdateInstantiated( existing.output );

          usedPoints.Add( hash );

          READ_ONLY_reusedPoints ++;
          return;
          
        }
      );

      var unused = new DictionaryList<PackedScene,InstantiatedScatterPoint>();

      foreach ( var vk in _instantiatedPoints )
      {
        var ip = vk.Value;

        if ( usedPoints.Contains( ip.hash ) )
        {
          continue;
        }

        unused.Add( ip.scatterPoint.scene, ip );
      }

      points.ForEach( p =>       
        {
          var hash = GetScatterPointHash( p );

          if ( usedPoints.Contains( hash ) )
          {
            return;                      
          }          

          if ( unused.ContainsKey( p.scene ) )
          {
            var unusedPoint = unused[ p.scene ].Find( ip => ip.scatterPoint.CanBeReusedBy( p ) );
            
            if ( unusedPoint != null )
            {
              unused.Remove( p.scene, unusedPoint );
              unusedPoint.scatterPoint = p;
              unusedPoint.scatterPoint.UpdateInstantiated( unusedPoint.output );

              usedPoints.Add( hash );

              READ_ONLY_remappedPoints ++;
              return;
            }
          }

          var instantiatedOutput = p.Instantiate();

          if ( instantiatedOutput == null )
          {
            return;
          }

          var ip = new InstantiatedScatterPoint();
          ip.hash = hash;
          ip.output = instantiatedOutput;
          ip.scatterPoint = p;

          if ( _instantiatedPoints.ContainsKey( hash ) )
          {
            Nodes.RemoveAndDelete( _instantiatedPoints[ hash ].output );
          }
          
          _instantiatedPoints[ hash ] = ip;
          usedPoints.Add( hash );

          READ_ONLY_instantiatedPoints++;
        }
      );


      Dictionaries.RemoveAll(
        _instantiatedPoints, ( k, v ) =>
        {
          if ( usedPoints.Contains( k ) )
          {
            return false;
          }

          Nodes.RemoveAndDelete( v.output );

          return true;
        }
      );

    }

    bool CanReuse( string hash, ScatterPoint sp )
    {
      if ( ! _instantiatedPoints.ContainsKey( hash ) )
      {
        return false;
      }

      var existing = _instantiatedPoints[ hash ];

      var canBeReused = existing.scatterPoint.CanBeReusedBy( sp );
      
      return canBeReused;
    }

    public List<ScatterPoint> Scatter( List<ScatterPoint> points )
    {
      var returnedPoints = _Scatter( points );

      if ( removeDiscarded )
      {
        returnedPoints.RemoveAll( p => ! p.visible );
      }

      return returnedPoints;
    }

    protected bool IsChildEnabled( Scatterer s, bool childrenNeedToBeVisible, bool childrenNeedToBeProcessing )
    {
      var enabled = true;

      if ( childrenNeedToBeVisible )
      {
        enabled = enabled && s.Visible;
      }

      if ( childrenNeedToBeProcessing )
      {
        enabled = enabled && ( s.ProcessMode != ProcessModeEnum.Disabled );
      }

      return enabled;
    }

    protected virtual List<ScatterPoint> _Scatter( List<ScatterPoint> points )
    {
      return points;
    }
  }
}